Sports Direct tycoon Michael Ashley has described a promise of a £15m payout to an investment banker as "drink banter".

Ashley has been dragged into a High Court dispute with ex-Merrill Lynch banker Jeffrey Blue, who says Ashley promised to award the multi-million pound payout if he increased Sports Direct's share price to £8. Ashley only gave Blue £1m for his work.

The promise was made at a management meeting in a pub, and Ashley is arguing the alcohol-fuelled agreement was not binding.

In a written statement, Ashley said Blue was "seeking to engineer something more" than he was entitled to.

However, Blue argued in a statement: "In making his offer to me Mr Ashley was not making a joke: he was being deadly serious about very large sums of money."

Yesterday the court heard how Ashley would regularly conduct rowdy management meetings in pubs. The tycoon would offer his top executives pints and kebabs while taking high-level business decisions, Blue has alleged.

"These meetings were like no other senior management meeting I had ever attended in all my years of investment banking experience," Blue said in a witness statement. "It was effectively a 'pub lock-in' with alcohol continuing to be served well beyond closing hours and fish and chips or kebabs being provided throughout the evening."

At one such meeting, Ashley vomited in a fireplace after a drinking competition, Blue told the court.

Ashley is set to take to the stand tomorrow, with his testimony expected to stretch into a hearing on Thursday. His firm is still recovering from reputational damage done last year when a parliamentary inquiry concluded his Shirebrook warehouse was run like a "Victorian workhouse".